Uticaj vakuum pakovanja na hemijske promene u ohlađenom goveđem mesu /The effect of vacuum packaging on chemical changes in chilled beef

The aim of the study was to establish the differences between chemical parameters of shelf life of unpackaged beef tenderloin and beef tenderloin packed in vacuum. Beef tenderloin used in the experiment, derived from 3 Simmental young cattle of av- erage weight of 400 kg, which were slaughtered in an industrial slaughterhouse.Dynamics of sample testing was: day 1 (after packag- ing), day 7, 14, 21 and 28. During storage, the packaged and unpackaged beef was tested in respect to chemical parameters that would indicate the hydrolytic and oxidative changes.The aw value, pH, acid number, TBA(Tiobarbituric acid) and TVB-N (Total volatile basic nitrogen) values were examined. The highest aw values were measured on day 21 of testing, in samples of packaged tenderloin from the fi rst and third cycle, while the lowest aw value was recorded on day 21 in samples of packed tenderloin from the second test cycle. All of the samples showed a decrease in pH during the fi rst 7 days, after which the pH value increased and in 14 day it was similar in pack- aged and unpackaged meat samples. During the investigated study period, acid value showed a permanent and rapid increase in the unpackaged meat in relation to sluggish increase, which was registered in the packaged meat. Based on the content of malondialdehyde (MAL) the vacuum packed beef tenderloin, in all three cycles, on day 1 of the test showed no presence of secondary oxidation products. In the fi rst two cycles of testing, from the 7 to 21 days, the amount of MAL increased, and in the third cycle, on day 7 and 14 of the test, the signifi cant increase in the MAL content was determined, while on day 21 and 28 of the test, its content signifi cantly decreased. The quantity of TVB-N,on day 1 of the test, in all three cycles of the tested samples of packaged and unpackaged beef tenderloin, was simi- lar, but on day 14 of testing, the content of TVB-N in unpackaged tenderloin was higher compared to the vacuum packaged tenderloin, what indicated to a faster protein degradation in unpackaged meat compared to the vacuum packaged meat. When the results obtained for the chemical parameters from the all three cycles are taken into accounts, it can be concluded that the shelf life of the unpacked beef was 14 days and for vaccum packed tenderloin 21 days.